The present invention relates to a method for producing a motor vehicle axle component.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
From the state-of-the-art it is known to produce motor vehicle axle components in particular from steel materials.
For this it is known from the state-of-the-art for example to first roll a steel strip and thereafter to form a motor vehicle axle component from the steel strip. For this purpose, the steel strip is cut to size and then formed into a control arm in the form of a control-arm shell for example by press forming or a deep drawing process. For this, it is also known in the state-of-the-art to directly form the steel strip into a tubular body or to first cut the steel strip to size and to then form a tubular body from the cut to size steel blank. The tubular body is welded, in particular longitudinal seam welded, and subjected to a further shaping so as to produce for example a torsional profile as transverse beam of a twist-beam axle. In this way it is also possible to produce motor vehicle stabilizers.
In this way, in particular closed torsion profiles of a twist-beam axle are produced, wherein first a tube is produced by a continuous welding process of a hot rolled steel strip, and subsequently normalizing is carried out at about 900° C. The thus produced tube is then brought into the desired shape in a further cold forming process for further processing into the twist-beam axle. Subsequent thereto an austenizing is performed, wherein the thus produced torsion profile is firstly heated to about 900° C. and subsequently hardened by fast cooling so that the austenite is transformed into martensite. After the hardening process a tempering at temperatures of about 200° C. to 500° C. can be performed depending on the desired properties. This results in a component with predominantly tempered martensite which depending on the annealing atmosphere may have a surface decarburization.
The thus produced component has a high hardness while possessing acceptable ductility. However, because a motor vehicle axle component, in particular a vehicle body part, is subjected to increased continuous alternating stress and bending stress during its use, material fatigue may occur and in particular cracks may form in the edge region. The motor vehicle axle component, in particular the motor vehicle axle, may then be damaged and would have to be exchanged after technical checking.
It is known from the state of the art to use higher quality materials with complex processing methods, in particular heat post treatment methods, which however at the same time is associated with higher production costs. In the vehicle classes in which in particular a twist-beam axle is used, the increase in production costs is often not economical.
It would therefore be desirable and advantageous to provide an improved method with which it is possible to produce vehicle axle components in a cost effective manner, which have the demanded strength properties and a significantly increased service life.